The present invention relates generally to the field of electrophotographic copiers and more specifically to apparatus for aiding in the insertion and removal of photoconductive drums from such copiers.
In an electrophotographic copier, in which a rotating drum with a photoconductive outer surface is used for creation of a latent electrostatic image, occasionally it becomes necessary to remove the drum in order to permit access for normal maintenance of the copier, to replace a worn out drum or otherwise restore it to its original optimum operating condition. In the normally cramped confines of the copier, in which a multitude of drum interacting components are necessarily close to the photoconductive surface, sometimes within a fraction of an inch, removal of the drum with its fragile surface presents several problems. Usually, the drum is removed from its rotational shaft by sliding it in an axial direction until it has been completely disengaged therefrom. Because of the tight conditions within the copier, any radial movement of the drum during removal can cause it to come into contact with one or more of the other operating components. This can result in either damage to the other components or even irreparable damage to an otherwise reusable drum. This radial movement is practically unavoidable unless removal and replacement are guided by appropriate means.
One structure for removing the drum uses guide rollers in contact with the fragile drum surface and in conjunction with a drum-enclosed support structure. Since the photoconductive surface is extremely fragile, the likelihood of potential damage to the drum through contact with the rollers can be very high, and even a small defect in the photoconductive surface can preclude its use.
It is therefore an object of this invention to provide drum removal guide apparatus which provides no contact with the fragile photoconductive surface of the drum and therefore cannot damage that surface.
Other objects of this invention are to provide a drum removal guide apparatus which can be adapted simply and economically to the existing structure of conventional copiers, and which is reliable, maintenance-free, and easy to use.
It is a further object of the present invention to provide drum removal guide apparatus without adding to the congestion in the area surrounding the drum.